I am having a hard time trying to understand the pecking order for diagnosis codes that have -use additional code to identify under a chapter then also -use additional code to identify underneath the code you are choosing.

For example:

Hypertensive diseases (I10-I16)

-it says to use additional code to identify Tobacco use etc…

Lets say I am coding I12.9 Hypertensive CKD

-it also ask to use additional code to identify the stage of CKD

So my question is what would be the pecking order for the “use additional” when coding for the scenario above?

I12.9

Z87.891

N18.9

OR

I12.9

N18.9

Z87.891

My initial thought would be start from the chapter guideline first then go down so I would code it I12.9, Z87.891 then N18.9 but I could be wrong.

Thank you